1. Field of the Invention
The present invention relates to an inkjet printer and a suction apparatus used therefor.
2. Description of the Prior Art
In a closed ink tank, the amount of air inside increases due to evaporation of the ink or the like, and ink may not then be properly supplied. Therefore, the increased amount of air must be exhausted outside the tank. When the air is exhausted by a negative pressure suction source, ink is exhausted together with the air. For this reason, if air suction tubes for ink tanks of respective colors communicate with each other, the inks diffuse and mix with each other. In order to prevent this, a conventional arrangement as shown in FIG. 1 has been proposed. Referring to FIG. 1, a recording head 1 has an integral unit of a plurality of subtanks storing inks of different colors therein. Each subtank has an inkjet nozzle. Main tanks 2 (only one is shown in the figure for the sake of simplicity) are respectively connected to the subtanks. A cap 3 seals the surface of the recording head 1 in which the nozzles are embedded and serves to prevent drying of the inks. A negative pressure suction source 4 has independent air suction tubes 5 which are respectively connected to the subtanks.
With the arrangement as described above wherein the air suction tubes 5 are arranged for the respective subtanks, mixing of different color inks may be prevented to a certain degree. However, since the different color inks are still mixed in the negative pressure suction source, the inks diffuse and mix with each other as they are drawn into the air suction tubes 5.
When air layers are present in the air suction tubes 5, the different color inks mix with each other due to formation of an ink head or a change in the air volume, which are respectively caused by inclination of the air layers or changes in temperature.
In this manner, the conventional arrangement requires a separate negative pressure suction source for ink suction in addition to a negative pressure suction source for air suction. Furthermore, an air suction tube must be connected to each subtank. This has prevented easy mounting of the arrangement on the printer, and has thus prevented a compact arrangement. When the recording head 1 moves together with a carriage, the air suction tubes provide a resistance and adversely affect the movement of the recording head 1.